> For the complete documentation index, see [llms.txt](https://quantumphp.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://quantumphp.gitbook.io/docs/packages/migration/contracts.md).

# Contracts

## Base migration class

Every runnable migration must extend `Quantum\Migration\Migration` and implement both methods:

```php
public function up(TableFactory $tableFactory): void;
public function down(TableFactory $tableFactory): void;
```

`up()` applies the schema change.

`down()` reverts it.

The manager rejects classes that do not extend `Migration`.

## File and class contract

The runner discovers `*.php` files from `base_dir()/migrations` and derives the class name from the file basename.

In practice, each file should define a class that can be instantiated by that basename and that class should inherit from `Migration`.

If the file loads but the class is not a valid migration, the package raises `MigrationException::invalidMigrationClass(...)`.

## Manager API

### `generateMigration(string $table, string $action): string`

Creates a scaffold file and returns the generated migration name without the `.php` extension.

Supported actions are limited to:

* `create`
* `alter`
* `rename`
* `drop`

### `applyMigrations(string $direction, ?int $step = null): ?int`

Runs the migration set in one of two directions:

* `MigrationManager::UPGRADE`
* `MigrationManager::DOWNGRADE`

Return value is the number of migrations processed.

Package behavior is exception-first, not "zero means nothing happened": when there is nothing to apply or revert, it throws `MigrationException::nothingToMigrate()` instead of returning `0`.

## Driver contract

The runner only accepts database configs whose `driver` is one of:

* `mysql`
* `pgsql`
* `sqlite`

Any other configured driver is rejected before migration work begins.

## Template caveats

The built-in templates are scaffolds for starting a migration file.

Before you run a generated file, complete these package-driven details:

* align the generated method signatures with the base contract: `up(TableFactory $tableFactory): void` and `down(TableFactory $tableFactory): void`
* define `$newName` in `rename` scaffolds before using the rename calls
* add the schema operations that belong in `create` and `alter` scaffolds after the initial table lookup
* fill in `down()` for `drop` scaffolds when you want a reversible rollback path

Treat generated files as a starting point, then finish them for the schema change you want to ship.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://quantumphp.gitbook.io/docs/packages/migration/contracts.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.